1. Field
Control channels can benefit from a search space arrangement. For example, an evolved or enhanced physical downlink control channel (E-PDCCH) in the long term evolution advanced (LTE-A) physical layer can benefit in its design from a search space arrangement.
2. Description of the Related Art
LTE downlink physical layer was previously based on common reference signals (CRS) but may later be based on more user equipment (UE) specific reference signals. Release 10 of LTE may be unable to fully provide the benefits of demodulation reference signal (DM RS) based transmission, because the system still relies on cell specific reference signals to demodulate control information. This leads to increased control overhead in the system.
In a relay physical downlink control channel (R-PDCCH) for a relay backhaul link, physical resource blocks (PRBs) can be shared semi-statically with first slot for E-PDCCH carrying downlink (DL) downlink control information (DCI) and second slot for E-PDCCH carrying uplink (UL) DCI or physical downlink shared channel (PDSCH). Also, in R-PDCCH design, PRB-level spectrum sharing (SS) may be supported.
In R-PDCCH, however, a search space is configured by indicating resource blocks where R-PDCCH may be present. Additional explicit component carrier element (CCE) index is not signaled. Further, for R-PDCCH, the UL and DL allocations are located in different physical locations—the different slots will carry information for each link direction.